Process and apparatus for producing filaments



Aug. 15, 1939. F. J. ToBlAs 2 PROCESS AND APPARATUS FOR PRODUCING FILAHENTS IN V EN TOR.

A T TORNEYS.

Patented Aug. 15, 1939 UNITED STATES PATENT FFICE PROCESS AND APPARATUS FOR PRODUCING FILAMEN'IS Application September 4, 1936, Serial No. 99,354

6 Claims.

The invention relates in general to rubber filaments and, in particular, to a process and apparatus for producing elastic rubber laments and to correlated improvements in a circulatory 5 system therefor.

In the preparation of elastic rubber laments from a rubber-containing liquid, it is necessary to maintain a uniform and constant flow of the liquid to the lament-forming means to avoid irregularity of diameter and interruption of the process. For example, in forming a filament by picking up latex on a member moving in contact with a flowing layer of latex, it is important that the layer has a constant velocity of flow and a uniformity of thickness. Otherwise the laments picked up will be non-uniform in diameter and in other properties.

Further, in forming' rubber laments by an extrusion process, it is necessary to maintain a constant head of latex whether the extrusion is effected by gravity alone or with the aid of an external compressive force.

In pumping a heat-unstable liquid such as latex, it is important that no heat be caused to develop by friction or from other sources. Further, it is essential to prevent extraneous substances such as lubricating oils and the like from mixing with the latex during circulation.

Therefore, it is a general object of the present invention to provide a process and apparatus for the production of rubber filaments of uniform diameter in a continuous manner.

It is a specific object of the present invention to provide in a rubber filament-forming appara- 35 tus, means for effecting the uniform and constant low of a rubber-containing liquid to the filament-forming device therein.

It is a further specific object of the invention to provide in a rubber filament-forming apparao tus, a circulatory system which will deliver a layer of latex having a uniform velocity and thickness.

It is another object of the invention to provide in a rubber lament-forming apparatus, a circulatory system in which no heat is developed during circulation and which is sealed to prevent the admittance of extraneous substances such as lubricants and the like.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

According to the present invention, rubber filaments having uniform diameters are prepared by collecting latex upon the surface of a filamentiorming member moving in contact with a layer of latex, circulating the latex through an endless path passing in contact with the lamenti forming member, positively producing a pulsating current of latex in one part of the path, changing the pulsating current of latex to a constant current of latex by feeding the pulsating current into a pool of latex and causing the latex to flow by gravity from the pool to the point of contact with the filament-forming member. The apparatus of the invention comprises, in combination, a filament-forming device, preferably aheated endless member adapted to form a filament by contacting a layer of latex, means to maintain a layer of latex in contact with the endless member and a latex circulatory system including a head for flowing' the latex by gravity into contact with the endless member and a diaphragm pump for restoring the unused latex to the head.

The invention accordingly comprises the several steps and the relation ci one or more of such steps with respect to each of the others, and the apparatus embodying features of construction, combinations oi` elements and arrangement of parts which are adapted to eiiect such steps, all as exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing, in which:

Fig. l illustrates, partly in section, the circulatory system of the invention in combination with one embodiment of a filament-forming device;

Fig. 2 is an enlarged cross-sectional view of the diaphragm pump shown in Fig. l; and

Fig. 3 is a bottom plan View of the pump of the apparatus of Fig. l.

Referring to Fig. l, there is shown a uid circulatory system A in combination with a filament-forming unit B. The circulatory system A comprises a frame structure 4l having a base portion 2 and a bracket 3 upon which is mounted a fluid container i connected to a diaphragm pump 5 by means of a flexible conduit 5, preferably made of rubber. The uid from the pump 5 is discharged through a conduit 'l to a reservoir 4. Connected with the reservoir il is a conduit 8 which communicates with container 4 and provides an overflow for the reservoir 4 to maintain a specified level therein. A flexible conduit 9 having a valve Sd is provided between the reservoir 4 and the box or container le of the filament-forming unit B. To complete the cycle, a

flexible conduit I I is provided between the box I0 and the container 4. Suitable lters F and F', such as cheesecloth or the like, may be provided in the vessels 4 and 4 respectively for straining the fluid passing therethrough.

It can be seen from this structure that the uid in the original container 4, flows downwardly by gravity into the diaphragm pump 5 and is caused to flow up to the reservoir 4 where a constant level is maintained by the return flow conduit 8. From the reservoir 4, the uid flows by gravity through the conduit 9 into the box I0 whereupon the fluid is picked up by a filament-forming device I2. The overflow in the box I0 is returned by gravity to the container 4.

The diaphragm pump 5 is actuated by a motor I3 mounted on a bracket I4 which in turn drives a pulley I5 through a belt or a chain I6. The pulley I5 is connected to and drives the worm I1 which in turn causes rotation of the gear I8 mounted on a shaft i9 which is provided with a cam 20. The cam 2G, upon rotation, causes oscillation of the element 2I mounted thereon. The element 2I is connected to a lever 22 by means of a shackle 23 having a pivot 24. On the lever 22, which is pivotally mounted at the point 25, there is mounted a shackle 25 which is connected to one end of a rod 21. Pivotally mounted at 28 at the other end of the rod 21, there are connected two parallel levers 29, one positioned on each side of an element 52 which will be described later, as shown in Fig. 3, the levers 29 being affixed at the pivot point 30 on the frame I. The levers 29 are bent upwardly at their center portion to contact a diaphragm 32 of the pump which will be described later.

To operate this pump-actuating system, the motor I drives the worm i1 which in turn rotates the gear I8 causing the cam 20 to oscillate the lever 22 which imparts a reciprocal motion to the rod 21 which transfers this motion to the diaphragm 32 of the pump 5.

In Fig. 2 there is shown an enlarged crosssection and in Fig. 3 a bottom plan of the diaphragm pump which comprises a dome shaped head 3l of rigid stainless steel and a circular diaphragm 32 of ilexible stainless steel which is reenforced by a rigid metal disc 33. The peripheries of the elements 3l and .'32, having a gasket 34 therebetween, are clamped together by means of rings 35 and 3G, the latter of which is fixed upon the frame I. The rings 35 and 33 are clamped together by means of bolts 31 and 38, the former being pivotally mounted on the ring 33 and adapted to swing into clamping engagement between two lugs 39 projecting laterally from the ring 35. A cylinder 48 is fixed at the center of the dome-shaped head 3i by a bushing 4iso and communicates through the aperture 4I to the space 42 within the pump. A valve 43 is positioned on a valve seat 44 within the cylinder 4Q. A cylinder 45 which is similar to cylinder 4Z) is clamped to the center of the flexible diaphragm 32 and its reeniorcing disc 33 by means oi a bushing 45d and communicates with the interior space 42 of the pump. A valve 48 is positioned on a valve seat 41 within the cylinder 45. To the lower end of cylinder 45 is aflixed a hollow head 52 which has a threaded neck 52a making liquid-tight connection with the cylinder 45. The conduit 6 is connected to the lower portion of the head :2 at

52a and thus communicates through cylinder 45` with the interior space 42.

In the operation of the diaphragm pump, the levers 29 are caused to oscillate and on their upward motion the diaphragm 32 is moved upwardly to decrease the volume of the space 42. During an upward stroke, the valve 46 remains fixed against its seat 41, thus allowing no fluid to back into the conduit 6. The valve 43 is lifted and the fluid caused to flow into the conduit 1. On the downward motion of the levers 29, the valve 43 is forced down against its seat, thereby preventing the fluid from flowing back into the space 42. During such downward stroke, the valve 45 moves upwardly permitting the fluid in the conduit 6 to flow into the space 42. During the operation of the pump, the head provided in the container 4 causes the fluid to flow into the space 42 which has been partially evacuated during the downward stroke of the levers 29. The lever 22 may have a scale S marked thereon so that the length of the stroke of the pump may be readily adjusted and set to give the desired rate of iiow.

The circulatory system is provided with means for cooling the filament-forming fluid with water, the water flowing through a conduit 49 into an outer jacket 50 surrounding the reservoir 4'. From this jacket, the water flows through a conduit 5I into a cooling jacket 53 surrounding ie container 4, the water being drained therefrom through a conduit Cooling fluid is passed through a pipe 54 to a jacket 55 surrounding the conduit 1. A conduit 55, attached to the upper portion of the jacket 55, is provided to cause the cooling fluid to be returned to the upper portion of the diaphragm pump 5 from which it is drained by means of the pipe 51. From this structure, it may be seen that the fluid circulated in the system is cooled at appropriate intervals throughout the circulatory system which is quite essential in handling heat-unstable fluids. The box I0 may be provided with a suitable cooling system (not shown).

The unit B may comprise a filament-forming device of the type disclosed in either of the pending Spencer applications, Serial Nos. 137,898 and 17,465. Essentially the unit B comprises a filament-forming member I2 which picks up fluid from the box I0. Fluid flows from the reservoir 4 through the valve 9a which controls the rate of flow into a well 53 and over a weir 59 in the form of a layer. The device I2 picks up part of the flowing layer, the balance oi which enters the overflow chamber B and thence back through conduit II to the container 4. The fluid picked up on the device l2 is coagulated to form a lament 6I which is stripped from the device I2 by a roller 62 and passed through a dusting box (not shown) and wound upon a suitable swift (not shown) in the usual manner. If desired, fluid boxes other than the type shown may be employed and any suitable number of boxes may be used for each filament-forming member.

The fluid from which the rubber filaments are made may contain` any suitable form of rubber such as a natural or articial dispersion or a solution of a natural or synthetic rubber or any appropriate mixture of the above. It is preferred to employ a natural rubber dispersion, such as latex, containing suitable fillers, coloring mattei', vulcanizing agents, accelerators and heat-sensitizers. Any suitable fluid having the desired temperature may be employed in the cooling system such, for example, as water, brine, etc. The parts of the apparatus which are normally exposed to the rubber-containing huid may be composed of stainless steel, chromium, glass or any suitable non-corrosive material.

A diaphragm pump is particularly advantageous for use in the circulatory system of the invention because the displacement and movement oi the diaphragm is small, so that substantially no heat is generated which would tend to cause coagulation of the latex within the pump and change its viscosity. Moreover, there is no fric.- tional movement of the parts which are in direct contact with the latex so that one avoids coagulation of the latex by friction as would occur in the case of a piston pump. There are no liquid seals in the diaphragm pump so that the latex is not contaminated by oils or other extraneous materials whereby the viscosity of the latex remains substantially constant in iiow throughout the diaphragm pump.

Since certain changes in carrying out the above process and in the constructions set forth, which embody the invention, may be made without departing from its scope, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

l. In an apparatus for forming rubber laments by collecting latex on the surface of a heated endless member moving in contact with a layer of latex, a. latex circulatory system comprising a latex reservoir, a second latex reservoir positioned above said iirst reservoir, a latex container having a weir positioned intermediate said reservoirs, and a diaphragm pump for lifting latex from the irst reservoir to the second whereby the latex flows by gravity to said container.

2. In a process for forming rubber laments, the steps comprising collecting latex upon the surface of a heated endless filament-forming member moving in Contact with a body of latex, maintaining a body of latex in contact with said member, producing a uniform flow of latex in said body by gravity from a. pool of latex positioned higher than said body and returning the unused latex from said body to the pool by means of a pulsating current.

3. In a process for forming rubber filaments in which a mass of latex is circulated through an endless path passing in contact with a lamentforming member, the steps comprising circulating a body of latex by means of a pulsating current, and changing said pulsating current to a continuous unidirectional current by feeding the pulsating current into a large pool of latex and causing the latex to now by gravity from said pool in contact with said filament forming member.

4. In a process for forming rubber laments in which a mass of latex is circulated through an endless path passing in contact with a iilamentforming device, positively producing a pulsating current in one part of said path, feeding latex by said pulsating current to a pool of latex and causing latex to flow by gravity from said pool to the lament-forming device.

5, In an apparatus for forming rubber lament-s, a latex container having a weir, a filament-forming device located and having means t-o form a filament by contact with the latex flowing over said Weir, said container being con,- nected to a first latex reservoir which is located above said latex container, said latex container being connected to said first latex reservoir so that latex ilows under gravity from said first latex reservoir to said latex container, a diaphragm pump having its outlet connected to said iirst latex reservoir, a second latex reservoir connected to the inlet of said pump, level-controlling means operative to remove latex in said first latex reservoir above a predetermined level thereof and to transfer said removed latex to said second latex reservoir, means connecting said latex container with the second latex reservoir and adapted to transfer the latex which has flowed over said Weir to said second latex reservoir.

6. In an apparatus for forming rubber laments, a latex container having a Weir, a filament-forming device located and having means to form a filament by contact with the latex iiowing over said Weir, said container being connected to a first latex reservoir which is located above said latex container, said latex container being connected to said first latex reservoir so that latex flows under gravity from said rst latex reservoir to said latex container, a. diaphragm pump having its outlet connected to said first latex reservoir, a second latex reservoir connected to the inlet of said pump, level-controlling means operative to remove latex in said rst latex reservoir above a predetermined level and to transfer said latex to said second latex reservoir, means connecting said latex container with the second latex reservoir and adapted to transfer the latex which has owed over said Weir to said second latex reservoir, the rst latex reservoir being located above the second latex reservoir, said level-controlling means comprising an overflow pipe having one end thereof in com.- munication with the rst latex reservoir and having its other end in communication with the second latex reservoir.

FRED J. TOBIAS. 

